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Surface electromyographic (sEMG) signal is used in the various fields of applications where the need exists to measure the activity of body muscles, such as brain-computer interfaces, game industry, medical engineering, and other practical spheres. Even more, the use of sEMG signal in the field of active prosthesis industry has become traditional for many years. However, despite the fact that the question of using it in the field of fingers prostheses is still open, in general, the sEMG signal required multichannel measuring devices or massive, voluminous equipment for precise recognition of hands or fingers movement. That is decreasing the possible portability and convenience of prostheses and as a consequence is increasing their final price. In this paper we propose a method of organizing the controlling and measuring unit of the prosthetic device based on artificial neural network (ANN) model and one-channel microcontroller based sEMG measuring system. The proposed ANN model works with only 4 input time-domain features of sEMG signal and provides an accuracy of 95.52% for classification of 6 different types of finger movements that makes it a good solution for next implementation in the system of prosthetic fingers or wrist devices.

Mathematical models of continuous structural members (beams, plates and shells) subjected to an external additive white noise are studied. The structural members are considered as systems with infinite number of degrees of freedom. We show that in mechanical structural systems external noise can not only lead to quantitative changes in the system dynamics (that is obvious), but also cause the qualitative, and sometimes surprising changes in the vibration regimes. Furthermore, we show that scenarios of the transition from regular to chaotic regimes quantified by Fast Fourier Transform (FFT) can lead to erroneous conclusions, and a support of the wavelet analysis is needed. We have detected and illustrated the modifications of classical three scenarios of transition from regular vibrations to deterministic chaos. The carried out numerical experiment shows that the white noise lowers the threshold for transition into spatio-temporal chaotic dynamics. A transition into chaos via the proposed modified scenarios developed in this work is sensitive to small noise and significantly reduces occurrence of periodic vibrations. Increase of noise intensity yields decrease of the duration of the laminar signal range, i.e., time between two successive turbulent bursts decreases. Scenario of transition into chaos of the studied mechanical structures essentially depends on the control parameters, and it can be different in different zones of the constructed charts (control parameter planes). Furthermore, we found an interesting phenomenon, when increase of the noise intensity yields surprisingly the vibrational characteristics with a lack of noisy effect (chaos is destroyed by noise and windows of periodicity appear).

The purpose of the study is elaboration of approach for determination of functioning of chosen muscles that are essential for gait performance (Tibialis Anterior, Rectus Femoris, Gastrocnemius Medialis, Biceps Femoris). The scope of the study involves the analysis of the symmetric planar motion performing in the sagittal plane of the body by applying planar multibody model and electromyography signals (EMG) registered over normal gait performance. The analysis is performed by applying two types of multibody model: six degree of freedom system and seven degree of freedom system. Inverse dynamics task was used to calculated joint moments influenced ankle joints, knee joints and hip joints. Applied model also described single support phase and double support phase by taking into consideration the model of interaction between the ground and the contact foot. The activity states of considered muscles are determined on the base of their average activations and sequences in time.

In this study we consider a 3-link biomechanical model of a human for simulating a forward fall. Individual segments of the human body are modelled as rigid bodies connected by the rotary elements which correspond to the human joints. The model implemented in Mathematica is constructed based on a planar mechanical system with a non-linear impact law modelling the hand-ground contact. Due to kinematic excitation in the joints corresponding to the hip and the shoulder, the presented fall model is reduced to a single-degree-of-freedom system. Parameters of the model are obtained based on the three-dimensional scanned human body model created in Inventor, while its kinematics (time histories of the angles in hip and shoulder joints) are obtained from the experimental observation with the optoelectronic motion analysis system. Validation of the model is conducted by means of comparing the simulation of impact force with experimental data obtained from the force plate. Finally, the obtained ground reaction forces can be useful in further studies, as a load conditions, for finite element analysis of the numerical model of the human upper extremity.

Forward falls on outstretched hands are caused by unexpected lost of stability and they are always related with different kinds of injuries. This paper takes attempt to explain and figure out the multifaceted problems of forward fall. In order to estimate the critical value of the force acting on the hands at the moment of impact on the ground, the relative simple mechanical model is proposed. Mathematical model is described by the second order differential equations obtained by the Newton–Euler method, and its parameters are identified and validated using experimental data from one of the recent paper. Some interesting results are obtained, presented and discussed. The presented numerical simulations show that the proposed model demonstrate good accordance with real tested objects presented in the literature. The model predicts the highest impact force and finally allows to simulate various scenarios of human falls.

In this paper, the theory of nonlinear interaction of two-layered beams and plates taking into account design, geometric and physical nonlinearities is developed. The theory is mainly developed relying on the first approximation of the Euler–Bernoulli hypothesis. Winkler type relation between clamping and contact pressure is applied allowing the contact pressure to be removed from the quantities being sought. Strongly nonlinear partial differential equations are solved using the finite difference method regarding space and time coordinates. On each time step the iteration procedure, which improves the contact area between the beams is applied and also the method of changeable stiffness parameters is used. A computational example regarding dynamic interaction of two beams depending on a gap between the beams is given. Each beam is subjected to transversal sign-changeable load, and the upper beam is hinged, whereas the bottom beam is clamped. It has been shown that for some fixed system parameters and with an increase of the external load amplitude, synchronization between two beams occurs with the upper beam vibration frequency. Qualitative analysis of the interaction of two noncoupled beams is also extended to the study of noncoupled plates. Charts of beam vibration types versus control parameters {q0, ωp}, i.e. the frequency and amplitude of excitation are constructed. Similar and previously described competitions have been reported in the case of two-layered plates.

The complexity of the human gait manifests itself by lots of parameters that can evoke different changes in the walking manner. They can be divided into two groups: inherent, like anthropometric features or peculiar psychomotor type, and those related to the external conditions. The aim of the paper is to analyze the influence of three parameters, i.e. external load, ground slope and gait velocity, on the locomotion characteristics and the gait stability. Within the framework of investigations for different values of the mentioned parameters a film registration of the trajectories of selected kinematic nodes during some gait cycles has been carried out. The obtained data was a subject of numerical calculation aimed at extracting the essential properties of the principal gait characteristics.

Chaotic vibrations of flexible non-linear Euler-Bernoulli beams subjected to harmonic load and with various boundary conditions (symmetric and non-symmetric) are studied in this work. Reliability of the obtained results is verified by the finite difference method (FDM) and the finite element method (FEM) with the Bubnov-Galerkin approximation for various boundary conditions and various dynamic regimes (regular and non-regular). The influence of boundary conditions on the Euler-Bernoulli beams dynamics is studied mainly, dynamic behavior vs. control parameters {ω p , q 0} is reported, and scenarios of the system transition into chaos are illustrated.

The paper presents dynamic simulation and experimental identification of a human forward fall model describing the process of “falling like a broomstick” on the outstretched arms. The model implemented in Mathematica allows one to estimate time histories of the ground reaction force in different scenarios of the fall process. These time series are applied as time-varying load conditions to the numerical analysis of the human radial bone model created from the computed tomography data. Finally, the obtained numerical results indicate that the strain criterion seems to be more useful for estimating the radius fracture site in comparison to the stress criterion.

The presented work contains the numerical strain analysis of a ribbed shell of a rotary drum with two riding rings rigidly fixed to the drum shell. In the first stage of the conducted research a numerical model of a cylindrical shell was built with two stiffening rings of dimensions corresponding to the common constructions used in chemistry or the cement industry. The boundary conditions were set according to the mentioned machines working conditions and the model was subjected to loads corresponding to real data. The correctness of the numerical model was verified by a comparison with the results obtained in analytical calculations. The Fursow method was used in the analytical method. In the next step the model had been extended to include the longitudinal ribs added within the drum around the perimeter of the cylindrical shell. The ribs work as lifting flights. The bulk material was lifted by the flights during the rotation of the drum allowing for convective heat exchange between the material intended for drying and the air inside the shell. The bulk material was treated as a rigid body and the cylindrical shell of the drum was analyzed under its dead load. The effect of temperature was omitted due to the fact, that the drying was carried out at the temperature not exceeding 80 °C, hence the variability of Young’s modulus was negligible. An analysis was performed with the use of numerical methods and commercial software ANSYS. The influence of the position of material loads on the stress and deformation reduction of the cylindrical shell and running ring was analyzed. As a result of the numerical simulations, the distribution of bending moments and the areas of greatest stress concentration and maximum strain were identified.

This chapter is organized in the following manner. Modelling of an orbital cavity using finite element method is presented in section 2. Finite element method (FEM) is one of the basic tools used for mechanical investigations of a skull, a pelvic bone, eye-socket and in reconstruction of a bony face deformed by congenital defects or injuries. For example, it was applied for modelling of a skull with gnathothisis (Boryor et al., 2008), for investigation of infant head injuries caused by impact (Roth et al, 2009) and for examination of facial skull dystosis of a child (Gautam et al, 2007). FEM served also for an radiological and mathematical analysis of facial deformation provoked by curved central axis of the skull (Iannetti et al., 2004). Furthermore, the method was utilized for modelling of orbit deformation being result of bunt injury (Al-Sukhun et al, 2006) and also for investigation of biomechanical properties of the orbit (Sander et al, 2006). The aim of the study is to develop the numerical model of a bottom arch of an orbital cavity using a FEM. Based on the data obtained from computer tomography, the model of a healthy orbit was proposed. The results obtained from numerical analysis may serve as a basis for further investigations concerning stresses and deformations in orbital implants, including a direct implant application. Due to its geometrical complexity the whole skull (and especially its facial part) modelling presents a substancial engineering problem. To resolve it one subject the area of interest (the surface or the space) to a segmentation by means of finite number of elements averaging the physical state of the body. To generate the maps of stresses, deformations and displacements prior to calculations, it is indispensable to prepare the geometrical and material data of the model. The main subject of section 3 is to present a model of a double layered pelvic bone and some phenomena during leg flexion, extension, adduction and abduction, using finite element method (FEM). In the musculoskeletal system, the pelvis is one of the most important bones. It is a support of whole body, transfer external and gravitational loads across sarco-illiac and

Oscillations of a plate subjected to a aerodynamic force are considered. The first part of the investigation is devoted to the establishment of the mathematical model and derivation of the governing partial differential equations. Also the condition for the Hopf bifurcation threshold is defined, corresponding to the flutter oscillations. In the second part the analytical predictions are verified numerically. Further numerical investigations show the existence of chaotic motion. Two different scenarios leading to chaos are examined.

The paper presents chaotic dynamics of a particular non-linear oscillator having Duffing type stiffness, van der Pol damping and dry friction. We first utilize an averaging technique to obtain informations regarding the bifurcation behaviour of the vibrating system and then we analyze numerically the chaotic behaviour of the oscillator for parameters near bifurcation curves. We also discuss and illustrate the influence of the dry friction on the behaviour of a strange chaotic attractor.